The use of plastic materials for the in situ relining of underground pipelines such as sewer and gas lines and water mains is well known in the art. In Vandingberg U.S. Pat. No. 1,736,293, leaky conduits are repaired by introducing a fluid sealing material into the interior of the pipe and then forcing of the material through the leaking apertures and/or joints under a head of pressure until the material filling the apertures and/or leaks has solidified and then removing the excess material. In Perkins U.S. Pat. No. 1,988,329, a pipe is lined using a spray apparatus and then a kind of troweling operation is utilized to smooth the coated interior of the pipe. In this prior art example, the protective coating is a "plastic like material as concrete". In Witska U.S. Pat. No. 3,144,880, sewer pipelines are repaired by dispensing a fluent sealing material into the pipe. Hight et al U.S. Pat. No. 3,211,573 discloses a system for repairing pipes by applying a plastic lining via an applicator which is inserted through an exposed end of the pipe. In Huisman U.S. Pat. No. 3,122,786, the pipe is internally lined by extruding the liner in place of the pipe. This system is used only above ground but has been utilized in other patent disclosures for pipe repair. Blount et al U.S. Pat. No. 3,123,101 discloses a system for repairing pipe lines in which an inflatable liner is used to form an annular space into which a mixture of bentonite and mud is injected. The inflatable casing can be left in the pipe as an additional liner. In Van Arp U.S. Pat. No. 3,885,521 an apparatus for coating the inner wall of a duct is disclosed in which forward and rearward axially displaceable pistons have a coating mass therebetween which is distributed on the interior duct surfaces and trailing polishing bristles are used to position the applied coating.
In Harper et al U.S. Pat. No. 2,794,758, a flexible tubular plastic liner is inserted either by reversing or everting the liner upon itself or by drawing it through a pipeline and using fluid pressure to cause it to engage and conform to the internal wall of the pipeline. The plastic liner may be caused to adhere to the internal wall surface by an adhesive on the external surfaces of the liner which would be the internal surfaces prior to everting. In Lang et al U.S. Pat. No. 3,132,062, a rigid liner is formed in situ by use of multiple lamina with a polymerizable compound or a thermosetting resin. In such system, pressure is maintained until the polymerizable compound is polymerized and/or the thermosetting resin has set and/or been cured, to provide a rigid liner inside the pipeline, collapse of the liner being prevented by the rigidity which the resin bond imparts to the laminated liner. In Rubenstein U.S. Pat. Nos. 3,532,132, 3,340,115, and 3,424,203, in place relining and repair of pipelines is disclosed using layers of resin absorbent fibrous reinforcing material impregnated with polymerizable polymeric resin composition which is cured in place. In Wood U.S. Pat. No. 4,009,063, a laminar structure is formed in situ using a tubular fibrous felt liner immersed in a resin, in which the felt is immersed in the resin just prior to installation. The resin is cured to form a hard rigid lining with felt imbedded therein, there being an outer plastic film which contacts the internal wall of the passage being relined and an inner plastic liner to form a liner composed of a laminate of non-woven felt sandwiched between an outer membrane and an inner membrane both which membranes are plastic sheets. In Wood U.S. Pat. No. 4,064,211, the liner is in the form of a flattened tube of felt which has been impregnated with a synthetic resin. In order to eliminate friction, the liner is supported buoyantly by a liquid which serves to carry the same. In Wood U.S. Pat. No. 4,135,958, instead of pre-impregnating the liner, a pool or quantity of resin is formed between the liner just before it everts to thereby avoid the weight of the resin creating riction as it is drawn on the inside of the previously applied liner. In the foregoing processes, there is no positive force applied to assure uniformly smooth walls with no wrinkles in the plastic liner and that the resin is uniformly distributed where desired in the resin absorbent material.
In accordance with the present invention, the walls of the underground pipeline are thoroughly cleaned, which in the case of a sewer system, is done by the use of angulated water jets at high pressure used to dislodge and clean the line. A television camera is used to perform an inspection of the line to determine what the defects are and to make a log of all ties and intersects. Thereupon, a felt liner, coated on the outside (the side nearest the sewer walls) with a fluid impermeable plastic film, such as polyethylene film, is installed. The polyethylene film can be installed prior to installation of the felt liner and can be installed simply by everting a polyethylene film tube using air pressure or the like or the polyethylene film as a tube can be telescoped over the felt liner or it can be formed by welding a seam along the longitudinal sides of the film directly over the felt liner. At any rate, the polyethylene film prevents absorption of water or other contaminating fluids by the felt liner so as to permit full absorption of the desired resin. A steel cable or rod is then passed from between the two ends of the liner being installed e.g. from one man hole to another. The upstream end of the felt tube is molded or otherwise sealed to the end of the end of the existing underground passageway. The still dry felt tube, mat or "bag" is then squeegeed, impregnated with a liquid resin material in an amount determined by the record of condition of the walls established by the T.V. scan squeegeed again and then the resin is immediately cured by applying hydraulic pressure and heat to the internal surfaces of the resin material which has been absorbed by the felt liner.
The process of impregnating the felt with the resin and at the same time assuring that all wrinkles, bubbles etc. are eliminated is performed by coupling at least a pair of squeegees to the steel cable and a chemical resin feed line to the chamber(s) formed between the two squeegees. Thus, the space between a leading squeegee and the trailing squeegee forms a travelling or moveable resin depositing chamber or appartus, the resin being sprayed upon the felt or a full chamber resin is provided and maintained under pressure by the feed line. At the same time, the rate of movement of the moveable resin chamber and/or the pressure on the liquid resin can be controlled so as to control the degree of resin impregnation. Moreover, the resin composition can be changed to control the type, quality and curing speed of the resin at any point in the underground passageway being relined, more resin being applied at certain points if desired or a different resin having different characteristics can be applied at different points in the line being relined. As noted above, the lead squeegee irons or smooths the internal surfaces of the felt and, in combination with the trailing squeegee, maintains a certain degree of tension on the felt without tearing the same. The trailing squeegee in addition to assuring uniformity and smoothness of the now resin impregnated felt, also has a trailing section which receives the everting end of a resin curing tube which specifically is made of polyethylene and is adhered in place upon curing of the resin.
When the depositing apparatus is placed inside the felt, a stand pipe is set against the pipe at the manhole wall. This stand pipe shall reach above the manhole ring and frame, the polyethylene bag having the same size as the fibrous or felt tube installed will be passed through the stand pipe folded over the outside bottom end of the stand pipe and clamped tightly in place. Water will then be introduced into the stand pipe forcing the polyethylene bag inside the line and against the upstream or trailing squeegee. As the apparatus is moved, this polyethylene bag will evert and immediately cover and apply pressure to the resin impregnated felt tube. The resin curing polyethylene tube is maintained full of heated water or steam under pressure so as to apply a uniform pressure to the resin impregnated felt tube immediately after the impregnation thereof so as to initiate the curing of the resin. In the preferred embodiment, the everting end of the polyethylene tube is inside the squeegee trailing section and applies pressure against the upstream or trailing squeegee so that immediately as the trailing squeegee passes by, pressure is exerted on the felt and, at the same time, the curing of the resin begins by virtue of the heated water or fluid inside the polyethylene tube. With the steel rod or cable being pulled at a set rate, the amount of resin being cured via a pump and mixing vehicle above ground is initiated to begin impregnating the resinous material into the felt immediately as the first squeegee smooths and irons the unimpregnated felt. The trailing squeegee, having the trailing rubber sleeve, in which is nested the everting end of the polyethylene tube, smooths the new resin impregnated felt so that, as it passes the resin impregnated felt, pressure is always applied to the resin impregnated felt, first in the resin impregnating chamber, second by the trailing squeegee and its trailing rubber sleeve, and then by the everting polyethylene tube with the heated fluid therein. When the depositing apparatus is moved, the everted polyethylene bag will immediately move due to the hydrostatic head. As the rubber squeegees or discs are moved down the pipe, the resin would immediately be covered by the everting polyethylene bag. The water inside of the everting polyethylene can be heated at the start of the process thereby cutting down on final cure time. Thus, there are positive forces acting via the squeegees to initially smooth and eliminate wrinkles and bubbles and other surface defects and then a fluid hydraulic pressure is utilized to maintain the side walls in the ironed condition until the resin is cured. Thus, besides the reduction in the time involved, the squeegeeing operation and the immediate application of hydraulic pressure via the everting tube and the immediate application of a curing temperature to the resin provides a smoother surface and faster installation time. Thus, as compared to the prior art, the finished relined wall has an improved quality in that the quality can be controlled and the time of installation is reduced.